PCS1430x2000 Large Hammer Crusher Rotor Weld Overlay Repair

Literature Overview

This 2014 publication by Lv Wencheng and Cao Xuezhai from Gansu Jinchang Jinni Group Dry Process Plant, published in Cement journal, documents the weld overlay repair of a PCS1430x2000 large hammer crusher rotor. Hammer crushers are critical equipment in cement raw meal and clinker grinding circuits, and the rotor is the most heavily loaded component. The rotor consists of a shaft with mounted hammers that impact and crush material, and the hammer mounting surfaces are subject to severe impact and abrasive wear.

Core Technical Content

Equipment Description and Failure Analysis

The PCS1430x2000 hammer crusher has the following key specifications:

Parameter	Value
Rotor diameter	1430 mm
Rotor length	2000 mm
Shaft diameter	~200-250 mm
Hammer count	8-12 per row, 2-3 rows
Base material	Q235 or Q345 carbon steel
Operating speed	500-800 rpm
Feed material	Limestone, clay, shale, or clinker

The primary wear locations on the rotor include:

Hammer mounting pin surfaces: Subject to impact loading and fretting wear
Hammer wear surfaces: Direct contact with material being crushed
Rotor body surfaces: Abrasion from material passing through the crusher
Baffle plate mounting surfaces: Impact and abrasion from material rebound

Repair Strategy

The authors describe a comprehensive repair approach that addresses multiple wear locations simultaneously:

Hammer Pin Surface Repair:

Complete machining of worn pin surfaces to restore diameter
Application of high-carbon martensitic overlay (2-3 mm thick)
Post-weld tempering at 550-600 °C
Final machining to original pin diameter specifications

Hammer Wear Surface Repair:

For hammers with acceptable base material thickness, overlay repair is feasible
For hammers with excessive wear, replacement is more economical
Overlay material: high-chromium iron or high-carbon martensitic steel
Overlay thickness: 3-5 mm per side

Rotor Body Surface Repair:

Identification of worn areas by thickness measurement
Localized overlay repair of worn sections
Use of medium-carbon or high-carbon steel overlay
Overlay thickness: 5-10 mm, depending on the degree of wear

Welding Process Details

The welding process used for the rotor repair is primarily manual metal arc welding (MMAW) with low-hydrogen electrodes:

Parameter	Value
Electrode type	Low-hydrogen, high-carbon martensitic
Electrode diameter	3.2 mm or 4.0 mm
Current	120-180 A (3.2 mm), 180-250 A (4.0 mm)
Voltage	22-28 V
Preheat temperature	150-250 °C
Interpass temperature	<250 °C
Weld bead height	3-4 mm
Total overlay thickness	8-15 mm

The preheat temperature is particularly important for the rotor repair because of the thick section size and the high carbon equivalent of the base material. Without adequate preheat, hydrogen-induced cracking is likely to occur at the weld interface.

Quality Control Measures

The authors emphasize the following quality control measures:

Pre-repair inspection: Ultrasonic testing of the rotor for internal defects, visual inspection of all weldable surfaces
Consumable verification: Batch testing of electrode chemistry and mechanical properties
Welder qualification: Welders must be qualified for the specific material combination and welding position
In-process monitoring: Regular checks of weld bead appearance, fusion quality, and dilution
Post-weld testing: Hardness mapping, magnetic particle testing, and dimensional verification

Engineering Practice Integration

The hammer crusher rotor repair case study provides several valuable lessons for engineering practice:

Timing of repair: Rotor repair should be performed when the hammer pin surfaces have been worn to approximately 70-80% of their original diameter. Delaying repair beyond this point increases the risk of pin failure and rotor imbalance.
Rotor balancing: After overlay repair, the rotor must be dynamically balanced to ensure smooth operation. The addition of overlay material can shift the center of gravity, and rebalancing is essential.
Assembly considerations: The repaired rotor must be reassembled with proper clearance between hammers and the crusher housing. Excessive clearance reduces crushing efficiency, while insufficient clearance can lead to jamming.
Preventive maintenance: The frequency of rotor repair should be tracked, and a maintenance schedule should be established based on the observed wear rates.

Common Defects and Solutions

Defect	Cause	Solution
Cracking	Insufficient preheat, hydrogen pickup	Increase preheat to 250 °C, use low-hydrogen electrodes
Poor fusion	Inadequate surface preparation	Grind to bare metal, remove all coatings and contaminants
Excessive dilution	Too much base metal melted	Reduce current, increase travel speed
Rotor imbalance	Uneven overlay distribution	Plan welding sequence to minimize distortion, balance after repair
Hammer loosening	Inadequate pin diameter restoration	Verify pin diameter after repair, use proper hammer pins

Study Insights and Implications

This publication is valuable for its practical focus on a real-world repair scenario. The detailed documentation of process parameters and quality control measures provides a useful reference for engineers working with hammer crusher equipment. The emphasis on preheat and interpass temperature control is particularly important, as the thick sections and high carbon equivalent of the rotor material make it susceptible to hydrogen-induced cracking. I would recommend that engineers also consider the use of flux-cored arc welding or submerged arc welding for larger repair areas, as these processes provide higher deposition rates and better weld quality consistency compared to manual welding. Additionally, the use of hot-wire TIG cladding for the hammer pin surfaces could provide improved bond strength and reduced distortion.